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As part of the pre-start checks executed by the controls, the
oil sump temp is compared to evaporator saturated
refrigerant temperature. If the oil temperature is less than
140° F (60° C) and less than evaporator saturated refrigerant
temperature plus 50 ^ F (27.8^ C), the start-up will be delayed
until either of these conditions is no longer true. Once this
temperature is conrmed, the startup continues.
The oil heater relay is energized whenever the chiller
compressor is off and the oil sump temperature is less than
140° F (60.0° C) or the oil sump temperature is less than the
evaporator saturated refrigerant temperature plus 53^ F
(29.4^ C). The oil heater is turned off when either of the
following conditions is true:
Oil sump temperature is more than 152° F (66.7° C)
Oil sump temperature is more than 144° F (62.2° C) and more
than the evaporator saturated refrigerant temperature plus
55^ F (30.6^ C).
The oil heater is always off when the compressor is running.
For chiller type 19XR2~E/V/D, oil pump will be energized
for 30 seconds after each 30 minutes of oil heat relay being
energized in order to stir the oil for more evenly distributed
heating.
For chiller type 19XR6/7, 30sec/30min time interval is
configurable in Service Parameters table->Oil Stir
Cycle(19XR6/7):
Option 0(No stir), there will be no oil stir;
Option 1(30s/30m), oil pump will be energized for 30 seconds
after each 30 minutes of oil heat relay being energized;
Option 2(1m/4h), oil pump will be energized for 1 minute
after each 4 hours of oil heat relay being energized;
Option3(Comb.0&1), for the rst 50 hours of chiller in not
running status, oil stir will execute as option1. After 50 hours
elapses, there will be no oil stir.
PIC 5+ can support variable oil pump control and this option
is only available for 19XR2~E currently. The terminal channel
is located in IOB1 AO1, and it is a 4~20mA signal. During
operation, PIC 5+ control system will modulate the VFD
speed to control the lubrication system oil pressure difference
to between 25psi and 35psi.
For the 19DV system, refrigerant is used to lubricate and cool
the compressor bearings. The refrigerant lubrication system
mainly includes refrigerant pump, four control valves,
evaporator and condenser lter, moisture removal desiccant,
bearing lter, liquid level switch and additive reclaim system.
When the chiller is powered on, the controller will maintains
liquid level in condenser oat chamber. Once operator push
start button, the system will go into prestart check process.
After prestart check ok, when refrigerant pump request is
on for pre-lube and the bearing pressure difference is less
than 5psi, if Liquid Level is not satisfy, then pump refrigerant
from evaporator to condenser until Liquid Level is satised.
Then,if evaporator temp plus leaving condenser water is less
than 10F, pump refrigerant from evaporator to condenser,
after bearing pressure difference reaches 12psi, keep lasting
for 20s unitil compressor is on; else if evaporator temp plus
leaving condenser water is equal or larger than 10F, pump
refrigerant from condenser to bearing and drain to condenser,
if refrigerant pump didn’t open for pumping liquid when
start, open refrigerant pump after 10s, and after then, when
bearing pressure difference reaches 12psi, keep lasting this
process for 10s until compressor is on.. During pre-lubrication,
if the bearing pressure difference is less than 8 psi for
continuously 8 seconds, the chiller will shutdown.
The compressor will run after the pre-lubrication process.
Refrigerant will be pumped to bearing and drain to
evaporator from condenser oat chamber. When chiller
shutdown, the condenser control valve will be closed and the
refrigerant will be pumped from evaporator to bearing and
drain to condenser.
When the chiller is off , always open evaporator control valve.
If liquid level is low, refrigerant will be pumped from
evaporator to condenser oat chamber until the liquid level
swith is on and last 1 minutes after that.
5.7.1 - Set Point
Set point can be congured at menu “Setpoint” at “USER”
access level.
The SETPOINT is determined by the HEAT/COOL MODE,
EWT OPTION, and ICE BUILD OPTION in the below table.
Cooling LCW Setpoint Heating LCDW Setpoint
Cooling ECW Setpoint Heating ECDW Setpoint
Ice Build Option is Disabled when Heat/Cool Mode is set to Heating.
When Ice Build Option is Enabled and ice build is active, the control point is the Ice
Build Setpoint and the controlled water temperature is leaving chilled water
temperature.
5.7.2 - Control Point
Capacity control is based on achieving and maintaining a
CONTROL POINT temperature, which is the sum of the
valid set point (from the SETPOINT screen) and a
temperature reset value.
In cooling mode, Control Point is equal to the set point plus
temperature reset, while in heating Control Point will be set
point minus temperature reset.
The control point can be viewed directly on the main screen
or “General Parameters” menu.
5.7.3 - Temperature Reset
Three types of chilled water or brine reset are available and
can be viewed or modied on the “Reset Conguration”
screen.
The default screen indicates when the chilled water reset is
active. Control point Reset on the “General Parameters”
screen indicates the amount of reset.
To activate a reset type, access the RESETCFG screen and
input all conguration information for that reset type.
RESET TYPE 1: 4 to 20 mA TEMPERATURE RESET
Reset Type 1 is an “automatic” reset utilizing a 4 to 20 mA
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